1. Field of the Invention
This invention relates to speeding up conventional processes for producing nonlinear polyesters such as the alkyds.
2. Prior Art
The manufacture of alkyds is well known. See, e.g., Solomon, The Chemistry of Organic Film Formers, p. 86, Wiley (1967); and Kirk-Othmer, Encyclopedia of Chemical Technology, Vol. II, p. 33, Wiley (2nd Ed., 1978).
Around 4-5% by weight of solvent may be used to remove water evolved but 15% has been reported (Bobalek et al., J.Appl. Polymer Sci. 8, 628 (1964)) to minimize loss of volatile reactants and production of insoluble reaction products. Higher percentages of solvent have been used at elevated pressure: U.S. Pat. No. 3,325,428 (1967).
Catalysts are also sometimes employed: Callahan et al., U.S. Pat. No. 4,045,392 (1977). In most cases, the catalyst is used to catalyze the transesterification of a glyceride with a polyol, not to catalyze the polyesterification reaction. The catalysts are usually ineffective for polyesterification and are generally omitted.